The Storm culture is revered in Australian sport and the Saints hope Slater can develop those values at St Kilda.

"Billy's sporting resume is second to none, and he will add great value to our club," Saints football manager Simon Lethlean said.

"He's been an impressive leader in his own right, but he's also been a key member of a culture that is highly respected across all sports.

"Over the course of the season, we identified that there was an opportunity to strengthen our leadership and development programs, and we think Billy can play an important role in that."

Slater finished his career on 319 NRL games, scoring 190 NRL tries, the second most in league history.

The fullback is a one-time Dally M Medallist, two-time Clive Churchill Medallist and one-time Rugby League Golden Boot winner to go with his two NRL premierships, eight State of Origin titles, and two World Cup wins.